[time-nuts] low power divide by 5

[jimlux]

On 7/1/20 11:21 PM, Gerhard Hoffmann wrote:
> 
> Am 02.07.20 um 00:35 schrieb jimlux:
>> On 7/1/20 1:41 PM, ed breya wrote:
>>
>>> Yeah, I know. I was just lamenting the lack of nice medium-density 
>>> count functions in 74AC. It's hard to beat the simplicity of a '390 
>>> when you 
>>
> 16 bore holes just to deploy 4 flip flops is not what I'd call 
> simplicity. And Fairchild
> recognized that as well. The 390 did not make it into the 1987 Fairchild 
> Advanced CMOS
> (FACT) data book.
> They expected other chips to sell better, like the 74ACT488 GPIB / HPIB 
> / IEEE488 bus
> interface. Ever used one? The market for Nixie clocks with one counter + 
> one decoder
> per digit must have been smaller, even back then.
> 
>>>
>>> Anyway, I've always liked having a wide assortment of MSI logic 
>>> devices available in all families, that you just hook up and it goes 
>>> - no setup, no programming. I've saved lots of counter types for 
>>> possible use. One obscure one is the MC14566, with divide 6 counters 
>>> for clock time readout and generation, in the old days.
>>
>> That's sort of the design goal for the 22V10 and earlier PAL devices - 
>> keep them in familiar DIP packages, power on the corners like the IC 
>> gods intended, and you can program it to replicate a whole variety of 
>> MSI functionality, often with the same pinout.
>>
>>
> Corner pinning for Vcc and GND is not what any gods intended. In FACT, 
> (pun intended)
> it's evil. Remember ground bounce? The corners are the worst locations 
> on a DIL chip
> you can find for that job. And fig leaf capacitors across the chip are 
> just that.

Certainly, but when wire wrapping that big panel, and using a different 
color of wire for the V+ and V-, it sure makes it easier. <grin>



> At 100 MHz, they simply are not there. The optical illusion helps only 
> to hide that.
> The 3  ACT chips on the experiment board posted yesterday reminded me of 
> the
> last pages of this:
> 
> < 
> http://www.hoffmann-hochfrequenz.de/downloads/experiments_with_decoupling_capacitors.pdf 
>  >
> 
> The golden times of logic design are now, not then!

I'm surprised nobody has suggested using the 12AX7 or 6J6 dual triodes.